Method of applying metallic coatings



Patented a... 26.1937

PATENT OFFICE METHOD OF APPLYING METALLIC COATINGS' Tadcusz Liban, Krakow, Poland N'o Drawing.

Application April 25, 1930, Serial In Germany August 18, 1925. Re- I newed November 20, 1935 12 Claims. (Cl. 91-702) This invention is a continuation in part of my application Serial No. 125,321 filed July 2'7, 1926 and relates to a new method of applying metallic coatings to ironor metal-articles and is par- 5 ticularly applicable in coating iron sheets and the like with zinc.

In coating iron sheets with zinc in a mechanical way the sheets are introduced into the metalbath by rotating iron-rollers and are then rem moved out of the metal bath by other rollers after the coating has taken place. The sheetremoving rollers dip partly in the metal bath and are themselves galvanized. It is a serious drawback that the transporting rollers at the exit side of the metal bath carry with them a pulpy layer of metal, the, thickness of which depends upon the time the rollers are in use, the ingredients of the metal bath, and some other circumstances. Moreover on the surface of th 'zinc-,

gobathlthere are constantly formed zinc-ashes or dross which are apt to stain therollers which on their hand, stain the sheets while being removed by the rollers from the bath. Finally the galvanized rollers become oxidized because they 25 are partly in constant touch with the air. This stains the rollers too.

In galvanizing with spelter the rollers have been cleaned hitherto by zinc ammonium chloride obtained by the use of salammoniac. But

30 the zinc ammonium chloride is apt to absorb about 50-60% of zinc so that a considerable amount of zinc is taken out of the bath.

In galvanizing with zinc aluminum alloy it is not possible to clean the rollers by salammoniac 35 or by zinc ammonium chloride as it hardlycombineswith aluminum oxide which is formed in' this case.

It is the primary object of the present invention to keep the rollers thoroughly clean and to 40 this end I have devised new means for cleaning the rollers which are very efiective. They are of advantage in zincing with spelter as they take 25-30% less zinc from the bath. Butin the first place they are satisfactory as regards to cleaning 45 the surface "of the galvanized rollers when the metal bath consists of a zinc aluminumalloy.

It is an essential feature of the invention that for cleaning of the rollers which partly dip in a metal bath of zinc or of zinc and aluminum 50 there is used an alkali-chloride (which in the presenceof aluminum will form alkali aluminum chloride) or a mixture or a product -of reaction of a fluorine compound with a salt selected 'from' the following group: zinc chloride, ammonium- 5 chloride, alkali chloride or double salt of alkalichloride, mixture of zinc chloride and ammonium chloride, mixture of zinc chloride and alkali chloride or double salt of alkali chloride, mixture of ammonium chloride and alkali chloride or double salt of alkali-chloride, mixture of am- 5 monium chloride, alkali-chloride ordouble salt of alkali chloride, and zinc chloride.

The metal bath is prepared by melting spelter in a vat with or without the addition of aluminum. The metal sheets to be galzanized aretlo after pickling introduced into the metal bath by rollers arranged normally above the metal-bath, At the entrance of the metal-sheets into the bath the latter is covered with a flux for dis-' solving the oxides on the surface of the metal- 15 sheets and of the bath. The entrance side'of the metal bath is divided by a partition wall dip-, ping partly into the bath from the exit-side. On the exit-side there are arranged the rollers for extracting the metal sheets after they have become galvanized. These latter rollers dip partly in the metal bath and are therefore themselves galvanized. They are apt to become soiled by the oxides of the bath and to stain the galvanized sheets while the latter leave the metal bath. It is now possible to clean the extracting rollers by any known flux for instance by salammoniac and zinc-chloride independently of the flux used at the entrance of the bath for deoxidizing the sheet metal, inasmuch as at the exit-side the V sheets are already galvanized and need not to be deoxidized. But I have found that an alkalichloride or a mixture of a fluorine compound with a. salt of the group named. above is very effective in cleaning the rollers so that the rollers can rotate with a greater velocity than hitherto so that the output of the zincing plant may be increased. This statement applies also to the zincing by means of the lead-bath process. In I this case the flux for deoxidizing the sheet metal covers the lead bath on the entrance-side of the bath while on its exit side a layer of zinc or of zinc-aluminum is floating. The extracting rollers dip partly in the zinc-layer and are a cleaned according to my invention by a layer of the new. salt mixture and its reaction products. For deoxidizing the sheet-metal a separate hot bath'of molten or dissolved salts may be used so that for the purpose of deoxidizing the metal sheets no flux is needed on the entrance side of the galvanizing bath or lead bath.

What I claim is:

l. The method of keeping clean the' rollers between which sheets to be galvanized are withdrawn. from the galvanized bath, comprising, ar-

ranging a bath of molten galvanizing metal selected from the group which consists of zinc, and zinc and aluminum, positioning the rollers so that they are partly immersed in the metal bath, overlying the metal bath with a layer of a substance selected from the group consisting of alkali metal chlorides and a mixture or reaction product of a fluorine compound with a salt selected fromthe group which consists of zinc chloride, ammonium-chloride, alkali-chloride, double salt of alkalichloride, mixture of zinc chloride and ammonium chloride, mixture of zinc chloride and alkali chloride, or doube salt of alkali-chloride, mixture of ammonium chloride and alkali-chloride or double salt of alkalichloride, mixture of ammonium chloride, alkalichloride or double salt of alkalichloride, and zinc chloride so that the rollers are in touch with the said layer,.and operating the rollers so positioned.

2. The method of keeping clean the rollersbetween which sheets to be galvanized are withdrawn from the galvanized bath, comprising, arranging a bath of molten lead, and a.layer of molten galvanizing metal selected from the group which consists of: zinc, and zinc and aluminium on the exit-side of the lead bath, positioning the rollers so that they are partly immersed in the molten metal, overlying the molten galvanizing metal with a layer of a substance selected from the group consisting of alkali metal chlorides and a mixture or reaction product of a fluorine compound with a salt selected from the group which consists of: zinc chloride, ammoniumchloride, double salt of alkali-chloride, mixture of zinc chloride and ammonium chloride, mixture of zinc chloride and alkali-chloride or double saltof alkali-chloride, mixture of ammonium chloride and alkali-chloride or double salt of alkalichloride, mixture of ammonium chloride, alkalichloride or double salt of alkalichloride, and zinc chloride so that the rollers are in touch with the said layer, and operating the rollers so positioned.

3, The method of keeping clean the rollers between which sheets to be galvanized are withdrawn from the galvanized bath, comprising, arranging a bath of molten galvanizing metal selected from the group which consists of: zinc, and zinc and aluminium, positioning the rollers so that they are partly immersed in the metal bath, arranging a salt-bath outside of the metal bath, overlying the metal bath with a layer of a substance selected from the group consisting of alkali metal chlorides and a mixture or reaction product of a fluorine compound with a salt selected from the group which consists of: zinc chloride, ammonium-chloride, double salt of alkali-chloride, mixture of zinc chloride and ammonium chloride, mixture of zinc chloride and alkali-chloride or double salt of alkalichloride, mixture of ammonium chloride and alkali-chloride or double salt of alkalichloride,

- mixture of ammonium chloride, alkalichlorideor double salt of alkalichloride, and zinc chloride so that the rollers are in touch withthe said layer, and operating the rollers so positioned.

4. The method of keeping clean the rollers between which sheets to be galvanized are withdrawn from the galvanized bath, comprising arranging a bath of molten lead, and a layer of molten galvanizing metal selected from the group which consists of: zinc, and zinc and aluminium on the exit-side of the lead bath, arranging a salt bath outside of the metal bath, and positicning the rollers so that they are partly, im-

mersed in the molten metal, overlying the molten galvanizing metal with a layer of a substance, selected from the group consisting of alkali metal chlorides and'a mixture or reaction product of a fluorine compound with a salt selected from the group which consists of: zinc chloride, ammonium-chloride, double salt of alkalichloride, mixture of zinc chloride and ammonium chloride, mixture of zinc chloride and alkali chloride, or double salt of alkali-chloride, mixture of ammonium chloride and alkali-chloride or double salt of alkalichloride, mixture of ammonium chloride, alkali-chloride or'double salt of alkali chloride, and zinc chloride so that the rollers are in touch with the said layer, and operating the rollers so positioned.

5. In a galvanizing process in which rollers are used for handling sheets to be galvanized for introducing such sheets into or withdrawing them from a galvanizing bath, such rollers coming in contact with the galvanizing metal, and with the atmosphere outside the bath, the steps of forming a bath of molten galvanizing metal selected from the group consisting of zinc, and zinc and aluminum, and passing the metal through such bath, and between such rollers in' the presence of a flux comprising a material selected from the group consisting of alkali metal chlorides and they mixtures or reaction products of a fluorine compound with a salt selected from the group which consists of zinc chloride, ammonium-chloride, alkali-chloride, double salt 01 alkali-chloride, mixture of zinc chloride and ammonium chloride, mixture of zinc chloride and alkali-chloride, or double salt of alkali-chloride, mixture of ammonium chloride and alkali-chloride or double salt ,of alkali-chloride, mixture of ammonium-chloride, alkali-chloride or double salt of alkali-chloride, and zinc chloride, whereby the rollers are kept clean.

6. In a galvanizing process in which rollers are used for handling sheets to be galvanized for introducing such sheets into or withdrawing them from a galvanizing bath, the steps of forming a bath of molten galvanizing metal selected from the group consisting of zinc, and zinc and aluminum, positioning the rollers so that they dip partly into the bath, and passing the metal through such bath, and between such rollers in the presence of a flux comprising a material selected from the group consisting of alkali metal chlorides and the mixtures or reaction products of a fluorine compoundwith a salt selected from the group which consists of; zinc chloride, ammonium-chloride, alkali-chloride, double salt of alkali-chloride, mixture of zinc chloride and ammonium chloride, mixture of zinc-chloride and alkali-chloride, or double salt of alkali-chloride, mixture of ammonium chloride and alkali-chloride or double salt of alkali-chloride, mixture of' ammonium-chloride, alkali-chloride or double salt of alkali-chloride, and zinc chloride, whereby the rollers are kept clean.

'7. ma galvanizing process in which rollers are used for handling sheets to be galvanized for introducing such sheets into or withdrawing them from a galvanizing bath, such rollers coming in contact with the galvanizing metal, and with the atmosphere outside the bath, the steps of forming a bath of molten galvanizing metal selected from the group consisting of zinc, and zinc and aluminum, and passing the metal through such bath, and between such rollers in the presence of a flux comprising alkali metal-chloride,

' whereby the rollers are kept clean.

8. The method of keeping clean the rollers between which sheets to be galvanized are withdrawn from the galzanizing bath, comprising arranging a bath of molten galvanizing metal selected from the group which consists of zinc,

and zinc and aluminum, positioning the rollers so that they are partly immersed in the metal bath, overlying the metal bathwith a layer of a material selected from the group consisting of alkali metal chlorides and the mixtures or reaction products of a fluorine compound with a salt selected irom the group which consists of: zinc chloride, ammonium-chloride, alkali-chloride, double salt of alkali-chloride, mixture of zinc chloride and ammonium chloride, mixture of zinc chloride and alkali-chloride, or doublesalt of alkali-chloride, mixture of ammonium chloride and alkali-chloride or double salt of alkali-chloride, mixture of ammonium chloride, alkali-chloride or double salt of alkali-chloride, and zinc chloride so that the rollers are with the said layer, and operating the rollers so positioned. I

9. The method of keeping clean the rollers between which sheets to be galvanized are withdrawn from the galvanizing bath, comprising,

arranging a bath of molten galvanizing metal selected from the group which'consists of zinc, and zinc and aluminum, positioning the rollers so that they are partly immersed in the metal bath, overlying the metal bath with a layer of alkali metal chloride, so that the rollers are in touch with the said layer, and operating the rollers so positioned.

in touch 10. A process for galvanizing ferrous articles comprising the steps of preparing a molten bath containing metallic aluminum, preparing a molten layer of a flux consisting of an alkali-aluminum chloride, which molten flux layer floats on the aluminum containing bath, and then introducing the articles to be galvanized into the galvanizing bath and removing them therefrom.

11. In a galvanizing process in which rollers are used for handling sheets to be galvanized for introducing such sheets into or withdrawing them from a galvanizing bath, such rollers coming in contact with the galvanizing metal, and with the atmosphere outside the bath, the steps of forming a bath of molten galvanizing metal selected from the group consisting of zinc, and zinc and aluminum, and passing the metal through such bath, and between such rollers in the presence of a flux comprising a mixture of a fluorine compound and an alkali-chloride.

12. In a galvanizing process in which rollersv TADEUSZ LIBAN. 

